Metallacarboranes in catalysis. 4. Structures of closo- and exo-nido

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2990

J. A m . Chem. SOC.1984, 106, 2990-3004

Metallacarboranes in Catalysis. 4. Structures of closo- and exo-nido-Phosphinerhodacarboranesand a [ (PPh,),Rh]+[nido-7-R-7,8-C2B9H,'1- Salt' Carolyn B. Knobler, Todd B. Marder,zaEugene A. Mizusawa, R. G . Teller, Judith A. Long,zbPaul E. Behnken,zcand M. Frederick Hawthorne* Contribution f r o m the Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024. Received June 29, 1983

Abstract: In contrast to the observed equilibrium between the closo and exo-nido tautomers of the bis(tripheny1ph0sphine)rhodacarborane formally derived from (PPh3)2Rh+and the [nido-7,8-p-( 1',2'-CH2C6HaCH2-)-7,8-C2BgHlo]ion, the crystalline solid obtained from this system has been determined to be pure [closo-1,2-~-{ 1',2'-CH2C6H4CH2-1-3,3(PPh,)2-3-H-3,1,2-RhCzBgHgI (I). However, when one of these PPh3 groups was replaced by P(C6H11)3(PCy,), [exonid0-6,1O-{(PPh,)(PCy,)Rh~-6,10-p-(H)~-7 $-p( 1',2'-CH&,H4CH2-)-10,1 1-p-(H)-7 ,8-C2B9H,](11) was the preferred isomer present in the solid. If the o-xylylene group bonded to the two carbon atoms of the C2B9 framework was replaced by a phenyl and a methyl group and the phosphine ligands were both PPh,, [exo-nid0-4,9-((PPh~)~Rhl-4,9-p-(H)~-7-Me-8-Ph-7,8-C,B,H,] (III), in which the BHB bridge was not located, was preferred in the solid. When this complex was heated in tetrahydrofuran solution in the presence of excess PEt3 a polytopal rearrangement of the carborane icosahedron took place. The structure of the resulting complex, [~loso-l-Me-2,2-(PEt~)~-2-H-8-Ph-2,1 ,8-RhC2B9H9](IV), is described. Reaction of the exo-nido complexes with certain two-electron donor ligands can result in displacement of the Rh from the carborane cage to generate (R = ( l'-closo-1',2'-C2B10H11)) (V) has an ion pair. The crystal structure of the salt [(PPh3)3Rh]+[nido-7-R-7,8-C2B9Hll]been determined. Compound I crystallized in the monoclinic space group P2,/n with a = 17.803 (7) A, b = 21.425 (6) A, c = 13.010 (4) A, (3 = 98.20 (2)", and Z = 4. Observed and calculated densities were 1.36 and 1.44 g cm-,, respectively. Diffraction data to 28 = 45" (Mo K a radiation) were collected on a Picker FACS-I diffractometer, and the structure was solved by conventional Patterson, Fourier, and full-matrix least-squares refinement techniques. The final discrepancy index was R = 0.0597, R, = 0.0550, for 2864 independent reflections. The molecule possesses icosahedral geometry in which Rh occupies a vertex and is also bound to two triphenylphosphine ligands and to a terminal hydride ligand in a pseudooctahedral arrangement in which the carborane cage can be considered to occupy three coordination sites. Both carborane carbons, adjacent to each other in the closo-3,1,2 arrangement, are bridged by an o-xylylene group. Although this closo solid exhibited closo-exo-nido equilibrium in solution, the closo-3,1,2 geometry of the molecule in the crystal was normal in all respects. Compound I1 crystallized in the triclinic centrosymmetric space group Pi,with a = 11.565 (2) A, b = 13.527 (5) A, c = 18.313 (6) A, a = 91.90 (4)", fl = 73.21 (4)", y = 102.10 (6)", and Z = 2. Observed and calculated densities were 1.20 and 1.23 g cm-,, respectively. Diffraction data to 28 = 50" (Mo Ka radiation) were collected on a Picker FACS-I diffractometer, and the structure was solved by conventional Patterson, Fourier, and full-matrix least-squares refinement techniques. The final discrepancy index was R = 0.0561, R, = 0.0529, for 5571 independent reflections. In I1 a Rh(PPh,)(PCy,) moiety is attached to a nido-C2Bg icosahedral fragment through a pair of three-center, two-electron M-H-B bonds, and the conformation about Rh is distorted square planar. Another bridging hydrogen atom was found bound to two boron atoms of the open face of the carborane cage. Compound 111crystallized in the monoclinic space group C z j c , a = 10.732 (3) A, b = 23.610 (8) A, c = 17.247 (6) A, p = 91.32 (2)", and Z = 4. Observed and calculated densities were 1.24 and 1.29 g cm-', respectively. Diffraction data to 28 = 50" (Mo Ka) were collected on a Syntex P2' diffractometer, and the structure was solved by MULTAN, Fourier, and full-matrix least-squares techniques. The final discrepancy index was R = 0.0613, R, = 0.0675, for 3104 independent reflections. In 111the stereochemical configuration about Rh is the same as that seen in 11; however, in the former species the attachment of Rh(PPh,), to the carborane fragment is through two B-H vertices which are adjacent to a single carbon atom. In 111, as in 11, this dual attachment is to a B-H vertex present in the open face and to a B-H vertex in the adjacent belt of five. In I1 neither of these boron atoms is adjacent to carbon. Compound IV crystallized in the monoclinic space group P2,/n, a = 12.905 (3) A, b = 13.855 (2) A, c = 16.201 (3) A, (3 = 91.46 (2)", and Z = 4. Observed and calculated densities were 1.28 and 1.29 g cm-), respectively. Diffractometer data to 28 = 50" were collected on a Syntex P21diffractometer, and the structure was solved by Patterson, Fourier, and full-matrix least-squares techniques and refined to a discrepancy index R = 0.039, R, = 0.049, for 3946 independent reflections. Although IV possesses icosahedral geometry resembling that of I, the bonding face in IV is CB4 while that in I is C2B3. In IV, the carbon vertex bearing the phenyl substituent has migrated to a position in the lower belt of five atoms and is nonadjacent to the methyl-substituted carbon. Compound V crystallized in the monoclinic space group P2,/c, a = 14.819 (4) A, b = 25.429 (6) A, c = 17.578 (4)A, fl = 98.65 (2)", and Z = 4. Observed and calculated densities were 1.257 and 1.267 cm-,, respectively. Rapid decomposition of the crystal forced discontinuation of data collection before a complete data set to 20 = 45" had been collected. Data were collected on a Syntex PI diffractometer (Mo Ka radiation) and the structure was solved by heavy-atom techniques and refined to a discrepancy index of R = 0.0757, R, = 0.0771, for 3319 independent reflections. The anion consists of a ~ l o s o - C ~ B , icosahedron ~H~, bonded to a nido-C2B9Hll-icosahedral fragment through carbon vertices. The Rh(PPh3)3 cation exhibits an unusual geometry: the ligand conformation about Rh is approximately planar with a T-shaped arrangement of the three PPh, ligands, and two of the carbon atoms of a phenyl ring occupy the remaining position of a very distorted square.

In the previous contribution of this series the syntheses and reactions of exo-nido-phosphinerhodacarboraneswere presented' without a detailed description of the determination of the molecular structures of these new species and related compounds. The present contribution describes five X-ray diffraction studies which supply these details. The origin of each of the five species examined is briefly presented below. 0002-7863/84/ 1506-2990$0l.50/0

A general synthesis of bis(ph0sphine)rhodacarborane complexes is simply the reaction of the Cs salt of the corresponding carborane nido monoanion (RR'C2B9Hlo)-with [(PPh,),RhCI] in benzene.'

( 1 ) For part 2 of this series see: Long, J. A,; Marder, T. B.; Behnken, P. E.; Hawthorne, M . F. J . Am. Chem. SOC.,second of five papers in this issue.

0 1984 American Chemical Society

Metallacarboranes in Catalysis. 4

J . A m . Chem. Soc., Vol. 106, No. 10, 1984 2991

Figure 1. Molecular structure of [closo-1,2-p-{1’,2’-CH&H&H,-]3,3-(PPhS),-3-H-3,1,2-RhC2B9H9] (I). Thermal ellipsoids are shown at the 50% probability level. Hydrogen atoms, with the exception of the terminal hydride, and phenyl groups on phosphorus have been omitted for clarity. Figure 2. Another view of I. The disposition of the [RhP2H] moiety with

The reaction of the o-xylylene-substituted carborane monoanion respect to the carborane fragment is depicted. with [nido-7,8-p-( 1’,2’-CHzC6H4CH2-)-7,8-C2B9Hlo][ (PPh,),RhCI] in benzene produced a solution which contained 1 and 2. The metal hydride H(3) is approximately trans to B(8), species exhibiting close-exo-nido tautomerism. However, crystals H(3)-Rh-B(8) = 168(3)”, and is nearly cis to the two carbon deposited from this solution were shown to be that of the closo atoms on the C2B3face. The two triphenylphosphine ligands are tautomer (I). Factors affecting this equilibrium have been disthus as far away from the bridging o-xylylene group as possible. cussed in an accompanying paper.l When one of the PPh, groups The overall geometry of the closo-RhC2B9system is not unusual. in I was replaced by PCy, (Cy = cyclohexyl), the exo-nido isomer Interatomic distances and angles are presented in Table I. The separated as the crystalline phase (11). When the o-xylylene group Rh atom exhibits pseudooctahedral coordination, with the carin the carborane anion was replaced with a methyl and a phenyl borane cage occupying three coordination sites and two phosphine group and this anion was reacted with [(PPh,),RhCI], the exo-nido ligands and the hydride ligand occupying the remaining sites. form [e~o-nido-4,9-((PPh,)~Rh)-4,9-k-(H)~-7-Me-8-Ph-7,8Bonding of the metal atom to the C,B, face is highly symmetric, C2B9H,] (111) was the crystalline product. with distances in the range 2.23 (1)-2.33 (1) A. Ion-pair species such as [(PEt3),Rh]+[nido-7-R-8-R’-7,8- It is interesting to compare I to the unsubstituted isomer CzB9Hlo]-react further to generate closo species’ of the general [~loso-3,3-(PPh~)~-3-H-3,1,2-RhC,B,H, (Ia). In contrast to formula [(PEt3)2Rh(H)(C,B9H9RR’)].When R = Me and R’ Ia, no asymmetry is found in the rhodium-phosphorus bonding, = Ph (but not when R, R’ = y-o-xylylene or y-CH2CH2CH2-) 2.335 (3) and 2.324 (3) A. These distances are nearly the average a polytopal rearrangement occurs, resulting in the formation of of the distances found in Ia, 2.357 (3) and 2.301 (1) A. As in [closo-1-Me-2,2-(PEt3),-2-H-8-Ph-2, 1,8-RhC2B9H9](IV). Ia, there is no evidence of interaction of the hydride ligand with Reaction of the exo-nido complexes with two-electron donor the carborane cage, and the Rh-H distance, 1.56 (9) A, is the ligands displaces the rhodium from the cage to give cationic species same as that found in Ia. The three angles around Rh involving of the type [L4Rh]+,[L3RhS]+,and [L2Rh(CO),]+ (L = PPh,) the hydride ligand and the two phosphorus atoms are slightly and [L4Rh]+ (L = PEt,). When [(PPh,),RhCl] reacted with smaller than in Ia, possible due to steric effects of the o-xylylene Tlf[nido-7-( 1’-closo-1’,2’-C2BloH1 ,)-7,8-C2B9HI in benzene, substituent. There is no crystallographic disorder in I because instead of an exo-nido compound, the salt [Rh(PPh,),]+[nidothe 0-xylylene substituent destroys the pseudosymmetry found in (V) was isolated as red 7 4 l’-closo-1’,2’-C2BloHll)-7,8-C2B9Hll]the C2B9 polyhedron in Ia. Indeed, the steric requirements of the crystals. The preparation and reactions of I-V are discussed in o-xylylene substituent may also explain the apparent lack of a companion paper’ while the structures of species I-V are rotation in solution of the [P2RhH]vertex with respect to the C2B, presented here. face of the carborane ligand.4 Molecular Structure of [exo-nido -6,10-((PPh,)(PCy,)Rh)Results and Discussion 6,lO-/.t-(H) 2-718-11-(1’,2’-CH&H4CH2-)- 10,ll-p-(H)-7,8-C2B,H7] Molecular Structure of [closo-1,2-p(l’,2’-CH,C,H4CH2-)(11). Three-center, two-electron M-H-B bonding (M = transition 3,3-(PPhJ2-3-H-3,1,2-RhC2B9H9] (I). In solution, [closo-1,2metal) is still a fairly uncommon phenomenon in exopolyhedral k - ( 1’,2’-CHzC,H4CH2-)-3,3-(PPh3)2-3-H-3,1,2-RhC2B9Hg] (I) metallaborane and metallacarborane c o m p l e ~ e s . ~The - ~ ~X-ray was found to be in equilibrium with its exo-nido tautomer, but structure of the exopolyhedral Rh(1) carborane complex the complex crystallized as the closo tautomer in which the hydride [(PPh3)2Rh(C2PhBloHlo)]has previously been reported;’ the ligand is projected over, and bisects, the C-C bond of the carRh-cage interaction consists of a Rh-C u bond and a Rh-H-B borane cage. In contrast, in the X-ray diffraction study of the l,2-RhC2B9Hl unsubstituted isomer [clos0-3,3-(PPh,)~-3-H-3, __ ___(la), only one of the atoms in the five-membered face coordinated (4) Marder, T. B.; Baker, R. T.; Long, J. A,; Doi, J. A,; Hawthorne, M. F. J . Am. Chem. SOC.1981, 103, 2988. to the Rh atom could be identified as a carbon atom, whereas the ( 5 ) Baker, R. T.; King, R. E., 111; Knobler, C. B.; OCon, C. A,; Hawtwo adjacent atoms required assignment as statistically disordered thorne, M. F. J . A m . Chem. Sot. 1978, 100, 8266. carbon and boron atoms. Thus the conformational preference of ( 6 ) Gill, J. T.; Lippard, S. J. Inorg. Chem. 1975, 14, 751. the unsubstituted complex is low. The closo tautomer of I probably (7) Paxson, T. E.; Hawthorne, M . F.; Brown, L. D ; Lipscomb, W. N Inorg. Chem. 1974, 13, 2772. exists in solution in the symmetric conformation shown in Figures (2) (a) University of California Regents’ Intern Fellow, 1976-1980. (b) University of California Chancellor’s Intern Fellow, 1977-198 1. (c) University of California Regents’ Fellow, 1979-1980. (3) Hardy, G. E.; Callahan, K. P.; Strouse, C. E.; Hawthorne, M. F. Acta Crystallogr., Sect. 5 1976, 532, 264. -_____-.__

(8) Colquhoun, H. M.; Greenhough, T. J.; Wallbridge, M . G. H. J. Chem. Soc., Chem. Commun. 1980, 192.

(9) Allegra, C.; Calligaris, M.; Furlanetta, R.; Nardin, G.; Randaccio, L. Cryst. Struct. Commun. 1974, 3, 69. ( I O ) Grimes [Grimes, R. N. In ‘Metal Interactions with Boron Clusters”: Grimes, R. N., Ed.; Plenum Press: New York, 19821 p 269 presents a recent review.

2992 J . Am. Chem. SOC.,Vol. 106, No. lo, 1984

Knobler et al.

,2-RhC,ByHy].2CH,CI, (I)' Table I. Intcrdtomic Di\tance5 (A) and Angles (deg) in [Ch0-1,2-p- {1',2'-CH,C,H,CH,-}-3,3-(PPh,),-3-H-3,1 ___-Rh( 3)-P(2) Rh(3)-P(3) Rh(3)-C( 1) Rh(3)-C(2) Rh(3)-B(4) Rh(3)-B(7) Rh(3)-B(8) Rh(3)-H(3) P(2)-C( 1 I ) P(2)-C(2 1) P(2)-C( 3 I ) P(3)-C(41) P(3)-C(S 1) P(3)-C(6 1) C(l)-C(2) C(l)-B(4)

C(l)-B(5)

2.335 (3) 2.324 (3) 2.292 (12) 2.310 (1 I ) 2.229 (14) 2.238 (15) 2.331 (14) 1.565 (88) 1.83 1 (9) 1.880 (8) 1.861 (9) 1.853 (9) 1.846 (8) 1.846 (8) 1.593 (17) 1.802 (18) 1.708 (19)

P(2)-Rh(3)-P(3) C(I)-Rh(3)-P(2) C(l)-Rh(3)-P(3) C(2)-Rh(3)-P(2) C(2)-Rh(3)-P(3) C(2)-Rh(3)-C( 1) B(4)-Rh(3)-P(2) B(4)-Rh(3)-P( 3) B(4)-Rh(3)-C( 1) B(4)-Rh(3)-C(2) B(7)-Rh(3)-P(2) B(7)-Rh(3)-P(3) B(7)-Rh(3)-C( I ) B(7)-Rh(3)-C(2) B(7)-Rh(3)-9(4) B(8)-Rh(3)-P(2) B(8)-Rh(3)-P(3) B(8)-Rh(3)-C( 1 ) B(8)-Rh(3)-C(2) 9(8)-Rh(3)-9(4) B( 8)-Rh(3)-9(7) P(2)-Rh(3)-H(3) P(3)-Rh(3)-H(3) C( l)-Rh(3)-H(3) C(2)-Rh(3)-H(3) B(4)-Rh(3)-H(3) B(7)-Rh(3)-H(3) B(8)-Rh(3)-H(3) Rh(3)-P(2)-C(I I ) Rh(3)-P(2)-C(2 1 ) C(1 I)-P(2)-C121) Rh(3)-P(2)-C(3 1) C(1 l)-P(2)-C(31) Ci21)-P(2)-C(3 I ) Rh(3)-P(3)-C(4 1 ) Rh(3)-P(3)-C(5 1) c ( 4 1 )-P(3)-C(5 I ) Rh( 3)-P(3)-C(6 1 ) C(41)-P(3)-C(6 I ) C(5 I)-P(3)-C(61) Rh(3)-C( 1)-C(2) Rh( 3)-C( I )-B(4) C(2)-C( 1 )-B(4) Rh(3)-C( I)-B(5) C(2)-C(1 )-B(S) B(4)-C( 1 )-B(5) Rh( 3)-C(l )-B(6) C(2)-C( I)-B(6) B(4)-C( 1)-B(6) B(5)-C( 1)-B(6) Rh(3)-C( I)-C(47) C(2)-C(I )-C(47) B(4)-C( 1)-C(47) H(5)-C( 1)-C(47) B(6)-C( I)-C(47) Rh(3)-C(2)-C( I ) Rh(3)-C(2)-9(6) C( 1 )-C(2)-9(6) Rh(3)-C(Z)-B(7)

98.7 ( 1 ) 106.2 (3) 151.9 (3) 144.3 (3) 111.9(3) 40.5 14) 87.8 (4) 148.9 (4) 47.0 (5) 75.6 (5) 159.8 (4) 87.0 (4) 74.1 (5) 45.0 ( 5 ) 77.8 (5) 113.1 (4) 106.3 (3) 75.9 (5) 76.4 (5) 44.4 (5) 46.9 (5) 78.1 (32) 75.1 (32) 97.1 (32) 91.9 (32) 135.8 (32) 122.1 (32) 168.0 (32) 114.5 (3) 118.1 (3) 99.5 ( 3 ) 115.9 (3) 106.7 (4) 100.0 ( 3 ) 122.3 ( 3 ) 109.7 (3) 101.1 (3) 119.0 ( 3 ) 96.4 ( 3 ) 105.8 ( 3 ) 70.4 (6) 64.7 ( 6 ) 1 10.0 (9) 123.1 (8) 109.9 (9) 62.5 ( 8 ) 127.5 (8) 62.0 (8) 112.0 (9) 60.4 (8) 109.4 18) 118.4 (IO) 125.6 ( I O ) 117.4 ( I O ) 111.7 ( I O ) 69.1 (6) 127.9 (8) 63.7 ( 8 ) 65.3 ( 6 )

C(I)-C(2)-9(7) B(6)-C(2)-8(7) Rh(3)-C(2)-B(I I ) C(l )-C(2)-B( 1 1) B(6)-C(2)-9(11) B(7)-C(2)-B( 11) Rh(3)-C(2)-C(48) C(I)-C(2)-C(48) B(6)-C(2)-C(48) B(7)-C(2)-C(48) B(ll)-C(2)-C(48) Rh(3)-9(4)-C(I) Rh(3)-9(4)-B(S) C(I)-B(4)-9(5) Rh(3)-9(4)-9(8) C(l)-B(4)-9(8) B(5)-9(4)-9(8) Rh(3)-B(4)-9(9) C(I)-B(4)-9(9) B(5)-9(4)-9(9) B(8)-9(4)-9(9) Rh(3)-9(4)-H(4) C(I)-B(4)-H(4) B(S)-B(4)-H(4) B(8)-B(4)-H(4) B(9)-9(4)-H(4) C(I)-B(S)-B(4) C(I)-B(S)-B(6) B(4)-B(S)-B(6) C(I)-B(S)-B(9) B(4)-9(5)-9(9) B(6)-B(S)-B(9) C(l)-B(5)-9(10) B(4)-B(5)-B( I O ) B(6)-9(5)-9(10) B(9)-B(S)-B( I O ) C(l)-B(S)-H(S) B(4)-B(S)-H(5) B(6)-B(S)-H(5) 9(9)-B(S)-H(5) B(lO)-B(S)-H(S) C(I)-B(6)-C(2) C(l)-B(6)-9(5) C(2)-9(6)-9(5) C(I)-B(6)-9(10) C(2)-B(6)-BiIO) B(5)-9(6)-9(10) C( 1)-9(6)-B( I I ) C(2)-9(6)-9(1 I ) B(j)-B(6)-B(ll) B( 10)-9(6)-B( 1 I ) C(I)-B(6)-H(6) C(2)-8(6)-H(6) B(S)-B(6)-H(6) B(IO)-B(6)-H(6) B(I I)-B(6)-€1(6) Rh(3)-9(7)-C(2) Rh(3)-B(7)-9(8) C(2)-9(7)-9(8)

Interat omic Distances 1.757 (19) B(7)-B(8) B(7)-B( 11) 1.518 (19) B(7)-B( 12) 1.730 (19) 1.740 (20) B(7)-H(7) B(8)-B(9) 1.691 (19) B(8)-B(12) 1.518 (17) 1.823 (21) B(8)-H(8) B(9)-B( I O ) 1.724 (23) B(9)-B( 12) 1.795 (21) B(9)-H(9) 1.242 (87) B( I O)-B( 1 I ) 1.744 (22) B( 1O)-B( 12) 1.746 (23) Bf lO)-H( 10) 1.716 (24) I . 1 34 (95) B ( l 1)-B(12) 1.687 (23) B(l l ) - H ( l I ) 1.7 17 (24) B(12)-H( 1 2 9 ) 1.160 (86)

1.821 (21) 1.768 (21) 1.798 (21) 1.022 (93) 1.726 (22) 1.798 (21) 1.063 (88) 1.754 (24) 1.78 1 (23) 1.078 (87) 1.754 (24) 1.792 (24) 1.142 (88) 1.759 (22) 1.016 (90) 1.096 (91)

Angles Rh(3)-9(7)-9(11) C(2)-9(7)-9(11) B(8)-B(7)-B( I I ) Rh(3)-B(7)-B(l2) C(2)-9(7)-B( 12) B(8)-B(7)-B( 12) B ( l 1)-9(7)-9(12) Rh(3)-9(7)-H(7) C(2 j-B(7)-H17) B(8)-B (7)-H( 7) B(ll)-B(7)-H(7) B( 12)-8(7)-H(7) R11(3)-9(8)-9(4) Rh(3)-B(8)-B(7) B(4)-9(8)-9(7) Rh(3)-9(8)-9(9) B(4)-B( 81-9 (9) B( 7)-9(8)-B(9) Rh(3)-9(8)-B(I 2) B(4)-8(8)-B( 12) B(7)-B(8)-B( 12) B(9)-9(8)-9(12) Rh(3)-B(8)-H(8) B(4)-9(8)-H(8) B(7)-9(8)-H(8) B(9)-9(8)-H(8) B( 12)-9(8)-H(8) B(4)-9(9)-9(5) B(4)-9(9)-9(8) B(S)-B(9)-9(8) B(4)-9(9)-B( IO) B(S)-B(9)-B( IO) B(8)-B(9)-B( IO) B(4)-8(9)-9(12) H(5)-B(9)-B( 12) B(8)-9(9)-B(I2) B(lO)-B(9)-9(12) 9(4)-9(9)-H(9) B(5)-9(9)-H(9) B(8)-9(9)-H(9) B( 10)-9(9)-H(9) B( 12)-9(9)-H(9) B(5)-H( 10)-9(6) B(5)-B(IO)-B(9) B(6)-B( 10)-B(9) B(S)-B(lO)-B(I 1 ) B(6)-B(IO)-B( 1 1) B( 9)-B( I O)-B( 1 I ) B(S)-B(IO)-B(I 2) B(6)-B(IO)-B(I 2) B(9)-B( I O)-B( 12) H ( 1 I)-B(10)-9(12) B(S)-B( I O)-H(IO) B(6)-B(IO)-H( 10) B(9)-B(lO)-H(lO) B( 1 I)-B(IO)-H( I O ) B( 12)-B( 1 O)-H( I O ) C(2)-B( 1 I)-H(6) CI2)-H( I 1 )-B(7)

123.4 (9) 57.6 (8) 106.7 ( I O ) 124.2 (9) 105.1 (10) 59.6 (8) 59.1 (9) 108.0 (50) 119.8 (50) 128.6 (SO) 114.8 (50) 120.2 (50) 64.7 (7) 63.9 (7) 104.5 ( I O ) 121.1 (9) 62.7 (9) 106.4 ( I 1) 119.3 (9) 110.3 ( 1 1 ) 59.6 (8) 60.7 (9) 109.5 (47) 125.2 (47) 121.9 (47) I 2 I .4 (47) 117.5 (47) 6 1.9 (9) 58.6 (8) 109.1 (11) 109.0 ( 1 I ) 58.7 (9) 110.8(11) 107.9 ( I I ) 107.6 ( I 1 ) 61.7 (9) 60.9 (9) 1 1 8.5 (47) 121.3 147) I 1 8.9 (47) 123.6 (47) 123.6 (47) 61.6 (IO) 60.4 (9) 1 1 1.1 (12) 106.7 (12) 59.8 (9) 107.0 (12) 108.5 (12) I 10.0 (1 2) 60.3 (9) 59.4 (9) 120.1 (44) I I I .5 (44) 128.0 (44) 119.5 ( 4 4 ) 126.6 ( 4 4 ) 6 1 .O (8) 60.4 (8)

110.0 (9) 1 11.7 (9) 123.3 (8) 1 1 I . I ( 10) 60.2 (8) 62.0 (8) 109.6 (8) 117.2 ( I O ) 110.6 ( I O ) 126.6 (10) 117.6 ( I O ) 68.4 (6) 120.8 (9) 56.2 (8) 71.0 (7) 107.5 ( I O ) 105.8 (IO) 123.2 ( 9 ) 102.0 (9) 57.7 (8) 58.7 18) I 1 I .9 ( 3 9 ) 107.4 (40) 103.3 (40) 143.1 (40) 123.9 (40) 6 1 . 3 (8) 61.2 (8) I 1 I .7 ( I I ) 108.1 ( 1 I ) 60.3 ( 9 ) 108.8 ( 1 1 ) 106.6 ( I 1) 109.5 ( 1 I ) 58.4 19) 60.9 ( I 0) 102.6 (45) 119.3 (45) 106.3 (45) 141.4 (46) 130.7 (46) 54.4 (7) 58.4 (8) 102.2 ( I O ) 105.7 (111 106.9 ( 1 I ) 60.0 (9) 102.5 ( 1 0 ) 58.8 (8) 107.2 ( 1 1 ) 62.0 ( 1 0) 104.8 (43) 109.4 (43) 121.6 ( 4 3 ) 141.8 (43) 131.2 ( 4 3 ) 69.7 ( 6 ) 69.2 ( 7 ) 107.4 ( I O )

C(47)-H(47 I ) C(47)-H(472) C(47)-C(7 I ) C(48)-C(76) C(48)-H(48 1) C(48)-H(482) C( 12M)-CI( 1) C(12M)-C1(2) C(34M)-CI( 3) C(34M)-C1(4) C(7 I)-C(72) C(7 1)-C(76) C(72)-C(73) C(73)-C(74) C(74)-C(75) C(75)-C(76)

B(6)-B(1 l)-B(7) C(2)-B( I 1 )-Bi I O ) B(6)-B( I 1)-B( I O ) B(7)-B(I I)-B(l0) C(2)-B(I 1)-B(12) B(6)-B( I l)-B(12) B(7)-B( 1 1)-B( 12) B( 10)-B( I I ) - B ( 12) C(2)-B(I I)-H(i I ) B(6)-B(l l)-H(l 1) B(7)-B(I I)-H(I 1)

0.826 (95) 0.789 ( 9 4 ) 1.484 ( 1 9 ) 1.482 (18) 1.017 ( 9 6 ) 0.877 ( 8 8 ) 1.705 (19) 1.802 ( 2 0 ) 1.677 (43) 1.629 (38) 1.390 (19) 1.372 (18) 1.418 (19) 1.409 (2 I ) 1.356 (20) 1.402 ( 1 7 )

1 1 1.0 ( 1 1 ) 105.6 ( 1 1)

58.1 (9) 108.9 ( I I ) 109.0 ( I I ) 110.2 ( I 1 ) 6 I .3 (9) 61.3 (9) I 17.8 ( S O ) 117.1 (50) 120.3 (50) 125.5 (50) B(IO)-B(II)-H(II) 124.7 (50) B(12)-B(1 1)-H(I I ) 60.9 (8) B(7)-9(12)-9(8) 105.2 ( 1 1 ) B(7)-B( I2)-9(9) 57.7 (8) B( 8)-B ( 12)-B( 9 ) 106.0 ( 1 1 ) B(7)-9(12)-9(10) 105.8 ( 1 I ) 9(8)-9(12)-B( I O ) B(7)-9(12)-B(I B(9)-9(12)-9(10)1) 58.8 (9) 59.6 (9) 108.2 ( I I ) B(8)-9(12)-B(Il) 105.7 ( 1 1 ) B(9)-B( I2)-B( 1 1) 59.2 (9) B( 1 O)-B( 12)-B( 1 1 ) 125.0 (47) B(7)-B( 12)-Hi 128) 119.0 ( 4 7 ) B(8)-B(12)-H(12B) 1 19.8 (47) B(9)-B( 12)-H( 1 2 8 ) B(lO)-B(I2)-H(12B) 123.3 (47) B( 1 l)-B( 12)-H( 128) 126.5 (47) Rh(3)-C(47)-C(I) 43.5 (6) Rh(3)-C(47)-H(471) 95.1 (65) C( I)-C(47)-H(47 1) 1 15.3 (66) Rh(3)-C(47)-H(472) 139.7 (68) C( l)-C(47)-H(472) 96.3 (68) H(471 j-C(47)-H(472) 109.5 (94) Rh(3)-C(47)-C(71) 91.6 ( 8 ) C(I)-C(47)-C(71) 116.0 (12) H(471)-C(47)-C(71) 110.3 ( 6 6 ) H(472)-C(47)-C(71) 108.2 ( 6 8 ) Rhi3)-C(48)-C(2) 43.5 ( 6 ) Rh(3)-C(48)-C(76) 93.7 (7) C(2)-C(48)-C(76) 1 18.0 ( 1 I) Rh(3)-C(48)-H(481) 80.6 (50) C(2)-C(48)-H(481) 102.3 ( 5 0 ) C(76)-C(48)-H(481) 113.0 ( 5 0 ) Rh(3)-C(48)-H(482) 144.8 (59) C(2)-C(48)-H(482) 104.3 ( 5 9 ) 1 18.6 ( 6 0 ) C(76)-C(48)-H(482) H(481 )-C(48)-H(482) 97.6 (77) CI(l)-C(I2M)-C1(2) 108.0 ( I O ) C1(3)-C(34M)-C1(4) 109.3 ( 2 1 1 C(72)-C(7 l)-C(47) 116.4 ( 1 2 ) C(76)-C(7 l)-C(4?) 124.1 ( 1 2) C(76)-C(7 1)-C(72) 1 19.4 ( I 2) C(71)-C(72)-H(72) 119.7 ( 1 2 ) C(71)-C(72)-Ci73) 120.7 (12) H(72)-C(72)-C(73) 119.6 ( 1 2 ) H(73)-C(73)-C(72) 120.9 ( 1 3 ) C(74)-C(73)-C(72) 1 18.1 ( 13) C(74)-C(73)-H(73) 121 .O 13)

J . Am. Chem. SOC.. Vol. 106, No. 10, 1984 2993

Metallacarboranes in Catalysis. 4 Table I (Contimted) Angles

H(74)-C(74)-C(73) C(73)-C(74)-C(75) H(74)-C(74)-Ci75) H(75)-C(75)-C(74) C(76)-C(75)-Ci74)

119.7(14) C(76)-C(75)-H(75) 120.5 (13) C(7 I)-C(76)-C(48) 119.8(14) Ci75)-C(76)-C(48) 119.6 (12) C(75)-C(76)-C(71) 120.8 (12) P(2)-C(ll)-C(12)

119.6 (12) 122.7( I 1) 116.8( 1 1 ) 120.4 (1 1) 122.0 (6)

P(2)-C(1 I)-C(16) P(2)-C(21)-C(22) P(2)-C(21)-C(26) P(2)-C(31)-C(32) P(2)-C(31)-C(36)

118.0 (6) P(3)-C(41)-C(42)

120.3 (5) ?(3)-C(41)-C(46) 119.7(5) P(3)-C(5 I)-C(52) 122.3 (6) P(3)-C(5 l)-C(56) 117.3 (6)

115.2 ( 5 ) 124.8(6) 119.415) 120.5 ( 5 )

Esd in parentheses in units of least significant digit of the corresponding value in this and in follouing tables

bridge bond. Prior to the discovery of the Ir exo-nido complexes" and the Rh species reported here, M-H-B bonding of exopoly86 hedral B-H units of nido-carborane fragments was only known with main group elements, the fluxional [exo-nido-9,10(R2M)-9,10-p-(H)2-10,11-p-(H)-7,8-C2B9H9]( M = Al, Ga, R2 81 = Me and Et).12 The structure of another exopolyhedral nidometallacarborane, [nid0-4,8-p-((Me~P)~Pt}-8,8-(Me~P)2-7,8,10CPtCBsHlo],has been reportedI3 in which one of the two Pt atoms is attached to a C2PtBs icosahedral fragment through one boron atom adjacent to the apical boron and through Pt in the open face of the cage. Although a variety of structural types have been established the spectroscopic and for 12-vertex nido-metalla~arboranes'~ analytical data available for the nido-rhodacarboranes described here did not allow unambiguous conclusions to be drawn concerning their structure and bonding. For example, cleavage of Figure 3. Molecular structure of [exo-nido-6,10-{(PPh3)(PCy,)Rhla C-B bond in the pentagonal bonding face would result in the 6,10-r-(Hr2-7,8-r-(1',2'-CH2C~H~CH2-)-7,8-C*B~H*] (11). Thermal Rh vertex interactin, with a "carbadiborallyl" fragment analogous ellipsoids are shown a t the 50% probability level. Hydrogen atoms, with to the structure of the tetracarbon metallacarborane [($the exception of bridging hydrides, and phenyl and cyclohexyl groups on C,H,)FeMe4C4B7Hs]1Sor the Rh atom could occupy a position phosphorus have been omitted for clarity. bridging a B-B edge above the open face, as found for main group O-P-(H)~-10,l l-p-(H)-7,8complexes [exo-nido-9,lO-(R2M)-9,1 and through the C2B3face is 38.7' (I) and 81.0' (11), as shown C,B,H,] (M = Al, Ga, R = Me, Et), referred to above,I2in which in Figures 1 and 3. the metal is bonded to the cage via a pair of three-center, twoMolecular Structure of [exo-nid0-4,9-((PPh~)~Rh]-4,9-pelectron M-H-B bonds.16 Consequently, in order to characterize (H),-7-Me-8-Ph-7,S-C2B9H8] (111). Some features of 111 can be these nido-rhodacarboranes, an X-ray structural analysis of I1 inferred from 'IB('H] N M R spectroscopy; e.g., the two upfield was undertaken. resonances, one of which is very broad in the decoupled spectrum, The empirical formula of I1 is identical with that of I except are reminiscent of upfield resonances in spectra of the parent for replacement of one triphenylphosphine ligand by tricyclonido-7,8-C2B9H1; ion, where one resonance is assigned to apical hexylphosphine. However, in I1 a (PPh3)(PCy3)Rh moiety is atom B( 1) and the other to the central boron atom in the open attached to a nido-C2B9icosahedral fragment through two exoface B(lO).I7 Atom B(10) is bonded to the bridging proton which polyhedral three-center, two-electron M-H-B bonds. Neither of tautomerizes between two positions, bridging either B(9) and B( 10) the two boron atoms involved in bridge bonding, B( 10) on the open or B(10) and B(11). The resonance usually appears to be C2B3 face and B(6) on the lower B, belt parallel to that face, is broadened due to poorly resolved coupling to the fluxional bridging bonded to carbon. The stereochemical configuration about rhoproton. In the 'H N M R spectrum of 111, a broad resonance at dium is distorted square planar, as shown in Figure 3. -2.15 ppm can be assigned to a bridging B-H-B. When the The greatest deviation of an atom from the least-squares plane sample solution is cooled to -88 'C, a broad singlet appears at through RhP2B2 is 0.262 (8) A (for B(10)), but the greatest -5.39 ppm, which can be attributed to Rh-H-B bridging protons. deviation of an atom from the plane through RhP2H2is 0.08 ( 5 ) N M R spectrum indicates the The sharp doublet in the 31P(1H) 8, (for H(10)). A bridging hydride is found bound to two boron apparent equivalence of the two phosphine ligands. The Rh is atoms of the open face. One of these boron atoms (B( 10)) is also bonded to an asymmetric cage; therefore, a process must occur bonded to an M-H-B bridging hydride. Interatomic distances which makes the two phosphines equivalent on the N M R time and angles are listed in Table 11. scale, such as rotation of the (RhL,) moiety perhaps coupled with The most striking difference in the nature of the o-xylylene a migration of the (RhL2)fragment about the polytopal surface substituents in I and I1 is at the points of attachment to the of the carborane ligand. Similar processes obviously occur in 11, carborane cage. The angle between the normals to the leastI11 and the various exo-nido species which we have previously squares planes defined by the two methylene carbon atoms and discussed' as determined by variable-temperature IH and 31P{1H) the two carborane carbon atoms and by the C2B3 face is 23.8" N M R spectroscopy. The lack of an apparent terminal Rh-H (I) and 34.7' (11) while the angle between the normals to the stretch in the I R spectrum suggests that 111exists purely in the least-squares planes through the eight o-xylylene carbon atoms exo-nido form in the solid state. The molecular structure of I11 is shown in Figure 4 and dis________ tances and angles are presented in Table 111. The structure ( 1 1 ) Doi, J. A.; Teller, R. G.; Hawthorne, M. F. J . Chem. SOC.,Chem. Commun. 1980. 80. formally consists of a discrete [(PPh3)2Rh]+fragment bonded to (12) Young,'D. A. T.; Wiersema, R. J.; Hawthorne, M. F. J . Am. Chem. ion. two terminal B-H bonds of a [nido-7-Me-8-Ph-7,8-C2B9Hlo]SOC.1971., 93.. 5687. The Rh atom interacts with B(4)-H(4) and B(9)-H(9) through (13) Barker, G. K.; Green, M.; Spencer, J. L.; Stone, F. G. A.; Taylor, B. two three-center, two-electron Rh-H-B bonds, each of which may F.; Welch, A. J . J . Chem. Soc., Chem. Commun. 1975, 804. (14) Pipal, J. R.; Grimes, R. N. J . Am. Chem. SOC.1978, 100, 3083. be formally considered as a two-electron donor to the metal, thus Maynard, R. B.; Sinn, E.; Grimes, R. N. Inorg. Chem. 1981, 20, 1201. completing the 16-e- configuration at the Rh(1) center. Grimes, R. N.; Sinn, E.; Pipal, J. R. Ibid. 1980, 19, 2087. (15) Maxwell, W. M.; Bryan, R. F.; Grimes, R. N. J . Am. Chem. SOC.

1977, 99, 4008.

(16) Churchill, M. R.; Reis, A. H., Jr.; Young, D.A. T.; Willey, G. R.; Hawthorne, M. F. J . Chem. SOC.,Chem. Commun. 1971, 298.

--____

( 1 7 ) Howe, D. V.; Jones, C. J.; Wiersema, R. J.; Hawthorne, M. F. Inorg. Chem. 1971, 10, 2516.

Knobler et al.

2994 J. Am. Chem. SOC.,Vol. 106, No. 10, 1984

Table 11. Interatomic Distances ( A ) and Anglcs (dcg) in [exo-nido-6,lO-{(PPh,~)(PCy,,)Rh~-6,1 0-p-(H)2-7,8-p-(1',2'-CH, C, H,CH,)- I O , 1 1-1.1(H)-7,8-C, B,,H,] (II)a 2.247 (2) 2.256 (2) 2.338 (8) 2.398 (8) 1.842 (47) 1.832 (50) 1.840 (4) 1.843 (5) 1.828 (4) 1.861 ( 7 ) 1.864 18) 1.861 (7) 1.730 ( 1 2 ) 1.747 (11) 1.775 (12) 1.778 ( 1 1) 1.770 ( 1 2) 1.017 (57) 1.719 (12) 1.760 ( 1 1) 1.725 (10) 1.811 (12)

B(2)-H(2) B(3)-B(4) B(3)-C(7) B(3)-C(8) B(3)-H(3) B(4)-B(5 B(4)-C(8) B(4)-B(9) B(4)-H(4) B( 5 )-B(6) B(5)-B(9) B(S)-B(lO) B(S)-H(S) B(6)-B(10) B(6)-B(1 1) B(6)-H(6) C(7)-C( 8) C(7)-B(I I ) C(7)-C(73) C(8)-B(9) C(8)-C(74) B(9)-B(10)

Interatomic Distances 1.077 (51) B(9)-H(9) 1.749 (11) B(IO)-B(ll) B(IO)-H(lO) 1.712 ( 1 1 ) 1.742 ( I O ) B(IO)-HB B(1 l)-H(I 1) 1.120 ( 5 5 ) 1.732 (12) B(1I)-HB 1.725 (10) C(41)-H(41) C(41)-C(42) 1.780 ( 1 2 ) C(41)-C(46) 1.141 (67) C(42)-C(43) 1.818 (11) 1.736 (11) C(43)-C(44) C(44)-C(45) 1.789 (12) C(45)-C(46) 1.076 (42) 1.712 (11) C(51)-H(51) 1.754 ( I O ) C(5 1)-C(52) 1.167 147) C(51)-C(56) C(52)-C(53) 1.558 (9) 1.602 (IO) C(53)-C(54) C(54)-C(55) 1.527 (9) C(55)-C(56) 1.626 ( I O ) C(61)-H(61) 1.539 (9) C(61)-C(62) 1.811 (12)

1.125 (56) 1.851 ( 1 1 ) 1.129 ( 5 5 ) 1.056 (63) 1.073 (51) 1.526 (60) 0.986 (64) 1.542 (10) 1.503 ( I O ) 1.533 (12) 1.482 (13) 1.493 (12) 1.532 (1 1) 1.060 (73) 1.507 (9) 1.520 ( I O ) 1.500 (11) 1.503 (11) 1.449 (12) 1.552 (13) 0.958 (74) 1.528 (10)

C(6 1)-C(66) C(6 2)-C(6 3) C(63)-C(64) C(64)-C(65) C(65)-C(66) C(7 3)-H(7 3A) C(?3)-H(73B) C(73)-C(8 I ) C( 8 1-C (74) C(?4)-H(7 4A) C(74)-H(74B) C(74)-C(82) C(83)-H(83) C(83)-C(84) C(8 3)-C(8 2) C(84)-H(84) C(84)-C(85) C(85)-C(86) C(85)-H(85) C(86)-H(86) C(8 1)-C(8 2) C(81)-C(86)

1.5 I 2 (1 I ) 1.535 ( I 1) 1.500 (13) 1.505 (12) 1.558 (11) 0.975 (74) 1.028 (70) 1.51 1 ( I O ) 1.539 (9) 1.038(61) 1.002 (71) 1.500 ( I O ) 0.892 ( 5 5 ) 1.377 (13) 1.381 (10) 0.849 (84) 1.370 (14) 1.389 (12) 1.013 (85) 0.986 (6 1) 1.381 ( I O ) 1.396 (11)

Angles P( 1 )-Rh-P(Z) P( 1)-Rh-B( 6 ) P(2)-Rh-B(6) P(I)-Rh-B(lO) P(Z)-Rh-B( 10) B(6)-R h-B( 10) P( 1 )-R h-H( 6 ) P(2)-Rh-H(6) B(6)-Rh-H(6) B( 10)-Rh-H(6) P(l)-Rh-H( 10) P(Z)-Rh-H( I O ) B(6)-Rh-H( 10) B( IO)-Rh-H( 10) H(6)-Rh-H( I O ) Rh-P( I)-C( 1 I ) Rh-P( I)-C(21) C(1 I)-P(l)-C(21) Rh-P(l)-C( 3 1) C( I 1 )-P(l)-C(3 I ) C( 21 )-P( 1 ) - ~ ( 31) Rh-P(2)-C(4 1 ) Rh-P(2)-C(S I ) C(41)-P(2)-C(5 I ) Rh-P(2)-C(6 1) C(41 )-P(2)-C(6 1 ) C(SI)-P(2)-C(6 I ) B( 2)-B( 1 )-B(3) B(2)-B( I)-B(4) B(3)-B( 1)-B(4) B( 2)-B ( 1 )-B (5 ) 8(3)-B(l)-B(5) B(4)-B( 1)-8(5) B(2)-B(I)-B(6) B(3)-B( l)-B(6) B(4)-B( 1 )-B (6) B(S)-B( 1)-8(6) B(2)-B( l ) - H ( I ) B(3)-B( I ) - H ( I ) B(4)-B(I)-H(1) B(S)-B(I)-H( I ) Bi6)-B(l)-H(l) B( l)-B(2)-B(3) B( I)-B(2)-B(6) B(3)-8(2)-H(6) B( l)-B(2)-C(7) B(3)-B( 2)-C(7) B(6)-B(Z)-C(7) B(I)-B(Z)-B(ll) B(3)-Bi2)-B( 1 1 ) B(6)-B(Z)-B( 1 I ) C(7)-8(2)-B( 1 I ) B( I)-B(2)-H(2)

99.3 ( I ) 149.0 (2) 111.3(2) 106.7 (2) 153.0 (2) 42.4 (3) 177.4 (14) 82.6 (14) 29.5 (14) 71.7 (14) 80.2 (16) 177.3 (16) 69.1 (16) 27.0 (16) 98.1 (22) 112.6 ( I ) I 10.0 (2) 103.9 ( 2 ) 125.7 ( I ) 100.4 (2) 101.6 ( 2 ) 114.5 (2) 11 2.9 (2) 104.7 (3) 115.0 (2) 105.0 (3) 103.7 (3) 59.3 ( 5 ) 108.3 ( 6 ) 59.5 (5) 110.7 (6) 106.5 (6) 58.4 (5) 60.4 ( 5 ) 105.7 (6) 106.8 (6) 61.7 ( 5 ) 117.6 (33) 124.0 (33) 125.8 (33) 122.4 (33) 119.9 (33) 60.9 (5) 60.9 (5) 107.4 (6) 104.5 (6) 59.6 ( 4 ) 99.0 (5) 108.3 ( 6 ) 105.7 ( 6 ) 58.8 (4) 53.8 ( 4 ) 130.4 ( 2 8 )

Rh-B(IO)-H(IO) B(S)-B( 1O)-H( I O ) B(6)-B( 1O)-H( I O ) B(9)-B( 1 O)-H( 10) B(l I)-B(lO)-H(lO) Rh-B( 10)-HB B(5)-B( 10)-HB B(6)-B( I 0)-HB B(9)-B(I OkHB B( I 1)-B( IO)-HB H( 1O)-B( IO)-HB Rh-B(I I)-B(2) Rh-B(Il)-B(6) B(2)-B(I 1)-B(6) Rh-B(l I )-C(7) B(2)-B(I 1)-C(7) B(6)-B(1 I)-C(7) R h-B( I 1 )-B( I O ) B(2)-B(ll)-B(IO) B( 6)-B ( I I )-B ( I O ) C(7)-B(l I)-B(lO) Rh-B(lI)-H(l I ) B(2)-B(lI)-H(ll) C(7)-B(1 I)-H(I I ) B(lO)-B(ll)-H(ll) Rh-B(l I)-HB B(2)-B(I I)-HB B(6)-B( 1 I)-HB C(7)-B(l I)-HB B( I O)-B( 1 1 )-HB H(1 I ) - B ( l I)-HB P( 1 )-C( 1 1)-C( 12) P( 1)-C( 1 1 )-C( 16) P( 1)-C(2 I )-C(22) P(I)-C(21)-C(26) P(l)-C(31)-C(32) P(I)-C(31)-C(36) P(2)-C(4 I)-H(4 I ) P(2)-C(4 I)-C(42) H(41)-C(4 1)-C(42) P(2)-C(4 1 )-C(46) H(4 I)-C(41)-C(46) C(42)-C(41 )-C(46) C(41 )-C(42)-H(42A) C(4 l)-C(42)-H(42B) C(4 1 )-C(42)-C(43) H(4 2A)-C(4 2)-C(4 3 ) H(42B)-C(42)-C(43) C(42)-C(43)-H(43A) Ci4 2)-C( 43)-H(43 B ) C(42)-C(43)-C(44) C(44)-C(43 )-H(43 A)

47.3 ( 2 6 ) 11 7.4 (27) I 1 3.8 (27) 129.6 (27) 123.4 (27) 116.2 (34) 138.5 (35) 114.4 (35) 87.7 (34) 5 5 . 5 (34) 101.8 (43) 103.6 (4) 48.2 (3) 59.1 (4) 149.1 (5) 60.4 (4) 104.2 (5) 50.5 (3) 106.1 ( 5 ) 56.6 (4) 105.7 ( 5 ) 87.2 (26) 118.7 (26) 123.4 (26) 124.8 (26) 72.4 (24) 132.8 (24) 91.4 (24) 98.6 (24) 34.8 ( 2 4 ) 108.2 (35) 121.4 ( 3 ) 118.6 (3) 120.8 (3) 119.1 ( 3 ) 119.6 (3) 120.3 ( 3 ) 106.5 ( 3 4 ) 117.6 (5) 93.0 (34) 113.2 ( 5 ) 114.7 (34) 110.4 (6) 109.1 (7) 109. I (7) 110.9 ( 7 ) 109.2 ( 7 ) 109. I ( 7 ) 109.0 ( 7 ) 109.1 ( 7 ) I 1 1.3 (7) 109.0 (8)

J . A m . Chem. SOC.,Vol. 106, No. 10, 1984 2995

Metallacarboranes in Catalysis. 4

_____-_________--

Table I1 (Continued)

___---

B13)-B( 2)-H(2)

123.9 (28) 126.0 128) 119.8 127) 115.2 (27) 59.9 15) 61.0 ( 5 ) 1 10.0 ( 6 ) 104.3 15) 60.4 ( 4 ) 103.9 ( 5 ) 103.4 ( 5 ) 103.3 ( 5 ) 59.2 ( 4 ) 53.6 ( 4 ) 133.1 ( 2 8 ) 120.0 (28) 126.9 (28) 115.0 ( 2 8 ) 119.9 128) 59.5 ( 5 ) 6 0 . 9 (5) 108.5 (6) 102.9 16) 60.2 (4) 100.7 ( 5 ) 107.4 (6) 107.7 16) 59.2 ( 5 ) 55.2 ( 4 ) 128.5 131) 118.0 131) 128.9 ( 3 1 ) 119.8(31) 119.9 ( 3 1 ) 60.7 15) 58.9 ( 4 ) 106.5 16) 109.2 ( 6 ) 6 I . 8 15) 104.9 ( 5 ) 107.3 ( 6 ) 1 1 1 . 2 16) 56.7 (4) 61.8 ( 5 ) 122.0 124) 129.0 ( 2 4 ) 1 1 6 . 8 124) 125.2 ( 2 4 ) 114.4 ( 2 4 ) 151.3 ( 5 ) 148.4 ( 5 ) 58.7 ( 5 ) 102.2 (4) 59.4 ( 4 ) 107.5 ( 5 ) 70.7 (4) 111.2(6) 114.9 ( 6 ) 6 0 . 8 (4) 97.7 (4) 109.0 ( 5 ) 62.0 15) 109.9 ( 5 ) 64.5 ( 5 ) 51.0 ( 2 3 ) 116.5 ( 2 3 ) I 1 8. I 123) 120.7 ( 2 3 ) 121.3 ( 2 3 ) 123.8 ( 2 3 ) 6 0 . 0 14) 11 1.4 ( 5 ) 64.2 ( 4 ) 65.8 (5) 116.2 ( 5 ) 111.7 ( 5 ) 123.0 ( 6 ) 115.9 ( 5 ) 1 1 5 . 1 15)

CI44)-C(43)-H(43B) C( 43)-Cl44)-H(44A) C(43)-C(44)-H(44B) C(43)-C(44)-C(45) C(45)-C(44)-H(44A) C(4j)-C(44)-H144B) C(44)-C(45)-H(45A) CI44)-C(45)-Hl45B) C(44)-C(45)-C(46) C(46)-C(45)-H(45 A) C(46)-C(45)-Hl45B) C(4 I)-C(46)-C(45) C(4 I)-C(46)-H(46A) C(4l)-C(46)-H(46B) C ( 4j)-C(46)-H(46A) C(45)-C(46)-H(46B) Pl2)-C(5 1)-H(5 1) Pl2)-C(5 1 )-C(52) H(5 1 ) - C ( 5 1 )-CIS21 P(2)-C(5 I)-C(56) C(56)-C( 5 1)-H(S 1) Cl56)-C(5 1 )-C(5 2) C(5 I)-C( 52)-H(52A) C(5 I)-C(52)-H(52B) CI 5 1)-C( 5 2)-C( 5 3) Hl52A)-C(5 2)-C(5 3) Hl52B)-C(5 2)-C(5 3) C(52)-C(5 3)-H(53A) C(5 2)-C( 5 3)-H( 5 3 B) C(52)-C(53)-C(54) Cl54)-C(53)-H(53A) C(54)-C(53)-H(53B) Cl53)-Cl54)-H(54A) C(53)-C( 54)-11(54B) C(5 3)-C(54)-C(55) C ( 5 5)-C(54)-H( 54A) C(55)-C( 54)-H( 54 B ) C(54)-C(55)-H(55A) C(54)-Cl55)-H(55 B) Cl54)-C(55)-Cl56) C ( 56 1-C( 55 )-H( 5 5 A ) Cl56)-C(55)-H(55B) C ( 5 I)-C(56)-C(55) C ( 5 1)-C(56)-H(56A) Cl55)-Cl56)-Hl56A) C ( 5 1 )-C(56)-Hi56B) C(55)-C(56)-H(56B) P(Z)-C(6I)-H(61) P(2)-C(6 I)-C(62) C(62)-C(61)-H(61) P(2)-C(6 I)-C(66) Cl66)-C(61)-H(61) C(62)-CL6 1 )-C(66) C(6 1 )-C(62)-Hl62A! C(6 I )-C(62)-H(62B) C(61 )-C(62)-C(63) H(6 2A)-C(6 2)-Cl6 3 ) H( 62 B)-C(62)-C(6 3 ) C16 2)-C(63)-H( 6 3 A) C(62)-C(63)-H(63B! Cl62)-C(63)-C( 6 4 ) C(64)-C(63)-H(63A) C(64)-C(63)-H(63B) C(63J-C(64)-H(64A) C( 63)-C(64)-H(64BJ C(63)-C(64)-C(65) H(64A)-C(64)-C(65) H(64B)-C(64)-C(65) C(64)-C(65)-Hi65A) Cl64)-Cl65)-H(65 B) C(64)-C(65 )-C(66 C( 66 )-C(65)-H(65 A ) C(66 )-C(65)-H(65B) C16 1 )-C(66)-C(65) C ( 6 1 )-C(66)-H(66A) C(65)-Cl66)-H(66A) C(61)-C(66)-H(66B) C( 6 5 )-Cl6 6 )- H ( 66 B ) C(7)-Ct73)-H(7 3 A )

109.0 ( 8 ) 108.9 ( 8 ) 109.0 ( 8 ) I 11.6 ( 8 ) 108.9 ( 8 ) 109.0 ( 8 ) 109.0 ( 7 ) 108.9 ( 7 ) 111.4(7! 109.0 ( 7 ) 109.0( 7 ) 112.1 ( 6 ) 108.8 ( 6 ) 108.8 ( 6 ) 108.8 ( 6 ) 108.8 ( 6 ) 103.4 (38) 111.8(5) 110.5 ( 3 9 ) 118.4 ( 5 ) 100.3 139) 1 1 I .4 (6) 108.7 16) 108.6 (6) 112.8 ( 6 ) 108.6 ( 6 ) 108.6 ( 6 ) 108.8 ( 6 ) 108.9 ( 6 ) 111.917) 108.9 ( 7 ) 108.9 ( 7 ) 108.5 17) 108.7 17) 112.7 17) 108.6 18) 108.7 ( 8 ) 108.5 ( 8 ) 108.6 ( 8 ) 113.1 ( 8 ) 108.6 ( 8 ) 108.5 ( 8 ) 109.9 ( 7 ) 109.4 ( 7 ) 109.4 17) 109.3 17) 109.3 ( 7 ) 106.6 144) 112.8 ( 5 ) 107.1 ( 4 4 ) 113.6 ( 5 ) 105.1 145) 111.1 (6) 109.0 ( 6 ) 109.1 16) 1 1 1 . 1 16) 109.0 ( 6 ) 109.2 ( 6 ) 108.8 17) 108.9 ( 7 ) 1 11.8 ( 7 ) 108.9 ( 7 ) 108.9 ( 7 ) 108.9 ( 7 ) 108.9 ( 7 ) 1 11.7 17) 108.8 (7) 109.0 ( 7 ) 109.3 ( 7 ) 109.3 ( 7 ) 110.1 17) 109.3 ( 7 ) 109.3 ( 7 ) 1 11.2 ( 6 ) 109.1 ( 6 ) 109.1 ( 6 ) 109.0 16) 109.0 16) 104.2 140)

2996 J . Am. Chem. SOC..Vol. 106, No. 10, 1984

Knobler et al.

Table I1 (Continued)

____--__

~~

B( 11)-C(7)-C(73) B(3)-C(8)-8(4) B(3)-C(8)-C(7) B(4)-C(8)-C(7) 13(3)-C(8)-B(9) B (4)-C( 8)-B(9) C17)-C(8)-B(9) B13)-C(8)-C(74) B(4)-C(8)-C(74) Ci 7)-C(8)-Ci 74) B(9)-C( 8)-C(74) B(4)-Bi9)-B(5) B(4)-B(9)-C(8) B(S)-B(9)-C(8) B(4)-B(9)-B( I O ) B(5)-B(9)-B( I O ) C(8)-B(9)-B( 10) B(4)-B(9)-Hi9) B(5)-B(9)-H(9) Ci8)-B(9)-H(9) B( 10)-B(9)-H(9) Rh-B(I 0)-B(5) Rh-B( 10)-B(6) B(5)-B(1 0)-B(6) Rh-B( IO)-B (9) B(S)-B( 10)-B(9) B(6)-BIl O)-B(9) Rh-B( I O)-B( 1 1) B(S)-BilO)-B(l 1) B(6)-B( 10)-B(I 1 ) B(9)-B(IO)-B(I 1)

120.6 ( 6 ) 60.6 ( 4 ) 6 2 . 2 (4) 1 1 2.2 (5) 115.4 ( 5 ) 64.1 (5) 116.0 (5) 115.5 ( 5 ) 121.6 (6) 113.7 15) 120.4 ( 6 ) 59.0 ( 5 ) 60.7 (4) 104.7 (5) 108.0 ( 5 ) 60.5 ( 4 ) 103.5 (5) 119.3 129) 125.2 ( 2 9 ) 12 1.4 (29) 125.8 ( 2 9 ) 100.8 (4) 66.9 ( 4 ) 62.5 ( 5 ) 156.1 ( 5 ) 57.7 ( 4 ) 106.2 15) 93.0 ( 4 ) 106.9 (5) 58.8 ( 4 ) 102.9 (5)

____

a

C(7)-C(73)-H(73B) H(73A)-C( 7 3)-H( 7 3B) C(7)-C(73)-C(8 1) C(8 I)-C(73)-H(73A) C(8 I )-C(73)-H(73B) C(8)-C(74)-H(74A) C(8)-C(74)-H(7 4B) Hi74A)-C(74)-H(74B) C(8)-C(74)-Ci82) C(82)-C(74)-H(74A) C( 82)-C(74)-Hi74B) C( 84)-C( 8 3)-H( 83) Ci8 2)-C( 83)-H(83) C( 82)-C(83)-C( 84) C( 83)-C(84)-H( 84) C( 83)-C( 84)-C(85) H(84)-C(84)-C( 85) C( 84)-C(85)-C(86) C( 84)-C( 85)-H(85) C(86)-C(85)-H( 85) C(8 l)-C(86)-C(85) C( 85)-C( 86)-H(86) C(81)-C(86)-H(86) C(73)-C(81 )-C(86) C(73)-Ci8 1)-C(82) C(82)-C(81 )-C(86) C(74)-C( 82)-C( 83) C(74)-C(82)-C(81) C(8 I)-C(82)-C(83) Rh-Hi6)-Bi6) Rh-HIlO)-B( 10) B(IO)-HB-B(lI)

Esd in parentheses in units of least significant digit of the corresponding value.

103.9 (37) 118.4 (54) 109.7 ( 6 ) 108.2 ( 4 0 ) 112.0 ( 3 7 ) 107.5 ( 3 3 ) 103.9 (39) 110.9 (5 I ) 110.6 ( 6 ) 110.9 (33) 112.7 ( 3 9 ) 122.0 (35) 117.6 ( 3 5 ) 120.0 (8) 115.2 (60) 1 2 0 . 8 (9) 123.9 (60) 119.6 ( 9 ) 128.1 (48) 112.3 (48) 120.0 (8) 121.5 (35) 118.5 ( 3 5 ) 121.2 ( 7 ) 119.3 ( 6 ) 119.5 ( 7 ) 121.9 ( 6 ) 1 18.0 ( 6 ) 120.1 ( 6 ) 99.5 (29) 105.7 (35) 89.7 ( 4 2 )

-_____-

-____

A

C41c

C51

Molecular structure of [exo-nido-4,9-((PPh3),Rhl-4,9-pL(H)2-7-Me-8-Ph-7,8-C2B9H8] (111). Thermal ellipsoids are depicted at the 50% probability level. All hydrogen atoms and the phenyl groups of the triphenylphosphine ligands have been omitted for clarity. Figure 4.

In 111, Rh is joined to the cage through two boron atoms which are adjacent to the phenyl-bonded carbon atom: B(9) on the open C2B3 face and B(4) on the lower B5 belt, parallel to that face, at distances of 2.40 (1) and 2.36 ( 1 ) A, respectively. These distances are somewhat longer than Rh(II1)-B distances found in the closo compound (I) of 2.24 ( l ) , 2.23 ( l ) , and 2.33 (1) A, but are very similar to those found in the exo-nido compound (11) where Rh-B is 2.338 (8) and 2.398 (8) A. Rh-P distances in I11 are 2.231 (4) and 2.232 (5) A while in I1 they are 2.247 (2) and 2.256 (2) A and in the closo compound (I) they are 2.335 (3) and 2.324 (3) A. In each compound, P-Rh-P is nearly orthogonal, 95.6 (1)' (111), 99.3 (1)' (11), and 98.7 (1)O (I), respectively. In 111 B(4) is approximately trans to P(l), B(4)-Rh-P(1) 151.6 (4)', and cis to P(2), B(4)-Rh-P(2) 111.9 (3)', and B(9) is approximately trans to P(2), B(9)-Rh-P(2) 154.9 (3)' and cis to P(l), B(9)Rh-P(l) 109.3 (3)'. The hydrogen atoms bridging B(10) and either B(9) or B(11) and Rh and B(4) were not located although the hydrogen bridging the Rh and B(9) was evident. The B(lO)-B(ll) distance, 1.84 (2) A, is not significantly different from B(9)-B(10), 1.81 (2) A, but is not normally found to be appre-

Figure 5. Molecular structure of [~loso-l-Me-2,2-(PEt,)~-2-H-8-Ph2,1,8-RhC2B9H9] (IV). Thermal ellipsoids are shown at the 50% probability level. Hydrogen atoms, with the exception of the terminal hydride, have been omitted for clarity.

ciably affected by the presence of B-H-B bridges. Although the bridging B-H-B proton on the open pentagonal face of the carborane cage was not located, spectroscopic data clearly indicated its presence.' The carborane cage retains the expected geometry of an 1 1-vertex icosahedral fragment, with no significant distortions induced by the exopolyhedral metal moiety; Le., the geometry of this fragment is not unlike that found in clos0-3,l ,2-RhC2B, icosahedra. Furthermore, a recent crystallographic study" of [exo-nid0-4,9-((H)~(P(p-tolyl)~)~Ir)-4,9-~(H)2-7,8-C2B9Hlo](Ha) showed it to possess entirely analogous metal-cage bonding interactions, and in this case both M-H-B hydrogen atoms were located. Unlike the exo-nido-Rh (1+) structures, the formal iridium (3+) complex (Ha) has two mutually cis terminal hydride ligands (not located crystallographically) bonded to Ir; thus the configuration around Ir would be expected to differ from that around Rh. However, there are many similarities, including the near

J . Am. Chem. SOC.,Vol. 106, No. I O , 1984 2991

Metallacarboranes in Catalysis. 4

Rh-P( I ) Rh-P(2) Rh-B(4) Rh-B(9) Rh-H(9) P(I)-C(Il) P(1 )-C(2I ) P( l)-C(3 1 ) P(2)-c(4 I ) P(2)-C(5 I ) B( I)-B(2)

2.231 ( 4 ) 2.232 (5) 2.36 ( I ) 2.40 ( I ) I .92 (8) 1.835 ( 5 ) 1.845 ( 5 ) 1.828 (6) 1.837 (6) 1.817 ( 5 ) 1.78 (2)

P( 1)-Rh-P(2) P( 1 )-Rh-B(4) P(2)-Rh-B(4) P( l)-Rh-B(9) P(2)-Rh-B (9) B(4)-Rh-B(9) P( I)-Rh-H(9) P(2)-Rh-H(9) B (4)-Rh-H (9) B(9)-Rh-H(9) Rh-P(I)-C(l I ) Rh-P( I)-C(2 I ) C ( I l)-P(l)-C(21) Rh-P(I)-C(3 I ) C( 1 1 )-P( l)-C( 3 I ) C ( 2 1)-P( 1)-c(3 I ) Rh-P(2)-C(4 1 ) Rh-P(2)-C(5 I ) C(4 1)-P(2)-C(5 1 ) Rh-P(2)